SACRAMENTO, Calif. (AP), A Central Valley lawmaker resigned unexpectedly Friday, creating a vacancy that dropped Democrats below the two-thirds threshold they need to pass tax changes or override vetoes. The loss, however, was expected to be temporary and not have major impacts on the majority party's clout.

State Sen. Michael Rubio, a moderate Democrat from the San Joaquin Valley town of Shafter, which is near Bakersfield, announced that he was stepping down immediately to take a government affairs job with Chevron Corp. He was in the middle of his first term in the Senate after being elected with 60 percent of the vote in 2010.

His resignation comes on top of recent vacancies but Democrats were already expecting to face difficulties in some of their goals later in the year, such as cementing a controversial $150 fee on rural residents whose homes are at risk from wildfires. Republicans, meanwhile, were expected to have a difficult time capitalizing on the vacancies in Democratic-leaning districts.

In a telephone interview with The Associated Press on Friday, Rubio said the job of a legislator had kept him away too often from his wife and two daughters.

"With me, family comes first. And over the holiday break, my wife and I, through a lot of thought and prayer, made a decision that I would not be running for re-election," he said.

At the same time, he said he learned of the job with Chevron, which he described as "a company that I have a great deal of respect for."

Rubio consulted his attorney and said he will not be lobbying. Neither he nor Chevron would disclose his salary with the San Ramon-based company.

"In this role, he will have responsibility for advancing the company's interests in California state politics and public policy, supervising a team of legislative and regulatory analysts and advocates in Sacramento," Chevron spokesman Morgan Crinklaw said in a statement.

State campaign finance records show Chevron gave the maximum contribution of $3,900 in each of the last two election cycles to Rubio's Senate campaign, for a total contribution of $7,800. Chevron donates to most lawmakers.

Rubio was making a base salary of $90,525 as a member of the Legislature along with daily expense payments that can add up to about $30,000 a year. California lawmakers do not receive pensions.

Rubio said his family will remain in Sacramento so his youngest child, who has Down syndrome, can receive care at the University of California, Davis MIND Institute, a research center that works on neurodevelopmental disorders.

Rubio's resignation temporarily drops Democrats to 26 seats in the 40-member Senate, one shy of a supermajority. That's because two Democratic-leaning seats are currently vacant.

Senate Democrats started the new two-year session with a 27-vote supermajority - instead of 29 - because Gloria Negrete McLeod of Chino and Juan Vargas of San Diego resigned their seats after being elected to Congress.

The outcome of special elections to fill their seats this spring could lead to vacancies in the 80-member Assembly, as Democrats that house run in the Democratic-leaning Senate districts.

Because Rubio is stepping down in the middle of his term, his 16th Senate district, which includes Kings County and parts of Fresno, Kern and Tulare counties, will hold a special election under the previous map, said Allen Hoffenblum, publisher of the California Target book, which analyzes legislative and congressional races. Democrats currently hold 50 percent registration compared to 28 percent for Republican in that district.

Even though the new district still strongly favors Democrats, Hoffenblum said it will be interesting to see if Republicans put up a fight.

"Republicans are so much talking about what they have to do to elect more Latinos, this might be a good opportunity to recruit a strong Latino and put a good race there," he said.

Assuming Democrats retain all open seats, there will be 29 Democrats and 11 Republicans in the Senate. Democrats hold 55 of the 80 Assembly seats, one more than needed for a supermajority, while there are 25 Republicans.

It's not clear who might succeed Rubio. Senate President Pro Tem Darrell Steinberg released a statement Friday wishing Rubio well in his new role.

"Michael is a good friend, a thoughtful policy maker, and his resignation is a tremendous loss to the Legislature, his constituents, and the State of California," Steinberg said.